Traveling wave tube electrode mountings



Feb. 7, 1961 E. c. DENCH TRAVELING WAVE TUBE ELECTRODE MOUNTINGS 2Sheets-Sheet 1 Filed Nov. 12. 1953 0 WC. 2 D m BY m ATTok/vEv Feb. 7,1961 E. c. DENCH TRAVELING WAVE TUBE ELECTRODE MOUNTINGS 2 Sheets-Sheet12 Filed NOV- 12. 1953 fivw-wron EDWARD C. DENCH wwg g0 ATTORNEY u ittdstfltt s Patent TRAVELING WAVE TUBE ELECTRODE MOUNTINGS Edward C.Dench, Needharn, Mass., assignor to Raytheon This invention relates toan electron gun mounting arrangement particularly adapted for use with atraveling wave electron discharge device and to such a device having anovel cathode for use with said electron gun.

Traveling wave electron discharge devices utilizing the interactionbetween an electron beam and one of the space harmonics of the RF wavetraveling along a periodic frequency responsive delay line are wellknown. One embodiment of a traveling wave tube suited for generationof'energy is shown and described in an application by E. C. Dench forU.S. Letters Patent, Serial No. 357,824, filed May 27, 1953. This tubeincludes a cylindrical periodic anode delay structure surrounding andconcen trically arranged with respect to a negative electrode or sole,thus forming an arcuate interaction space. A heated cathode positionedadjacent the sole serves as a source of electrons. These electrons,under the combined influence of an electric field established betweenthe anode and cathode and a magnetic field transverse to the electricfield, are permitted to encircle the aforesaid interaction spaceprovided that the magnitude and polarity of the two mutuallyperpendicular fields are properly adjusted.

Improved operation may often be achieved by the use of an acceleratorelectrode positioned adjacent the emitting area of the cathode. Thiselectrode, which is maintained at a positive potential relative to thecathode and sole, is instrumental in directing and shaping the electronbeam prior to its entrance into the effective interaction space.

Furthermore, where modulation of a traveling wave tube oscillator isdesired, a grid electrode may be provided adjacent the cathode in muchthe same manner that grids are utilized in receiving tubes. The gridserves to modulate the electron beam and thereby effects tuning of theoscillator.

The cathode assembly used with the traveling wave tube of the aforesaidcopending application has characteristics which are not suitable forcertain applications. Because the cathode in the aforesaid applicationis a directly heated ribbon of tungsten, the temperature forsatisfactory emission is relatively high, being of the order of 2,300degrees C. Due to the relatively large heating current flowing indirectly heated cathodes of the prior art, the 1ead-in conductors mustbe of substantial size and the traveling wave tube must be capable ofradiating a considerable amount of heat. The mean life of the directlyheated tungsten cathode previously used in traveling wave tubes isapproximately 200 hours thus necessitating frequent maintenance orreplacement of tubes in associated equipment. This cathode, like alldirectly heated r v 1C? cathodes, is productive of hum because of thevoltage drop across the ribbon and may cause variations in the tubemagnetic field.

One of the features of this invention is an improved cathode whichcomprises an elongated substantially polygonal block of porous tungstencoated with a layer of an emitting material which may, for example,contain a compound of barium. This block may be rectangular although thesurface exposed to the interaction space should be substantiallyparallel thereto. For example, if a linear tube is contemplated, thesurface of the cathode block adjacent the interaction space may beplanar and parallel thereto. If the tube is circular, the surface of thecathode adjacent the anode or the interaction space may be slightlyarcuate, so as to be concentric with the anode. For many purposes,however, the rectangular cathode may be satisfactory even when used witha circular tube. The cathode contains an aperture in which a low voltageheater is inserted. This heater may be of folded construction, such asused in standard receiving tubes, in which case the elfects of the straymagnetic field surrounding the heater may be substantially reduced. Theheater may be coiled instead of folded construction. This cathodeoperates at a temperature of the order of 950 degrees C. as comparedwith 2,300 degrees C. for directly heated tungsten cathodes. Since thecathode is indirectly heated, hum troubles are minimized and the timerequired to reach a stable operating temperature is reduced. Theincreased emissivity of this cathode together with the lower operatingtemperature result in an average cathode life in excess of 2000 hours.The amount of heating power required is quite low, being less than tenwatts under normal conditions. Because of the low heater current,smaller lead-in conductors may be used with resultant saving of spaceand weight of the traveling wave tube.

Another feature of this invention is an improved method of mounting thecathode, as well as other electrodes, if any, of the tube electron gun.Cathode mounting assemblies of the prior art have been comparativelybulky, complex and difficult to manufacture and assemble. Furthermore,in prior tubes utilizing an accelerator electrode, the latter is mountedon the inner rim of the anode by means of an insulator. The spacingbetween the cathode, which is supported from the sole, is subject totolerances of both sole and anode and to variations in the relativepositions of said sole and anode. This variation in spacing isundesirable since it has a direct effect upon the accelerating field,for a given accelerator voltage, and, consequently, afiects thetrajectory of the beam as it enters the interaction space.

Pursuant to this invention an electron gun mounting arrangement isobtained which may be easily and accurately assembled and which mayreadily be installed as a complete unit on the sole of the travelingwave tube. Each of the electrodes forming part of the electron gun isprovided with supporting leads or rods fixedly attached to eachelectrode. These supporting leads are passed through apertures in a pairof spaced electrically insulating supports and protrude from the surfaceof said supports. These apertures are stamped out in a predeterminedspaced relationship corresponding to the desired electrode array. Thesupports may be provided with metal eyelets which are inserted in theapertures and bent over at the edges. The supporting leads are thenPatented Feb. Z, 1961 secured to these eyelets, thereby supporting saidelectrodes in an accurate spaced relationship with one an other. Theinsulating supports are then mounted to oppositely disposed portions ofthe sole structure. A portion of the sole may be cut away to accommodatethe cathode heater and the grid and accelerating electrode, if

any.

To prevent the undesirable formation of a conductive film on the surfaceof the iiisulating supports owing to the gradual evaporation of theemitting material-from the cathode, a plate forming an extension of thesole flange and positioned over the electrode-containing slot in thesole may be used as an end shield. In tubes utilizing a grid, protectionof the insulating supports from an accumulation of cathode material mayalternatively be provided by means of end caps forming a part of thegrid and positioned above the ends of the cathode. Since most of theevaporating emitter material moves toward the ends of said cathode, thegrid caps need only cover the ends of the cathode body.

In the drawings:

Fig. 1 is a central cross-sectional view, partly in elevation, of atraveling wave tube according to the invention;

Fig. 2 is a detail view of a portion of the anode assembly of thetraveling wave tube of Fig. 1;

Fig. 3 is a view of the electron gun mounting assembly attached to thesole of the traveling wave tube of Fig. 1;

Fig. 4 is a view of the cathode and heater used in the assembly of Fig.3;

Fig. 5 is a detail view showing a modified cathode mounting arrangement;

Fig. 6 is a view of an electron gun mounting assembly including anaccelerator and a capped grid in addition to the cathode and heater ofFig. 3;

Fig. 7 is a fragmentary edgewise view of the mounting assembly of Fig. 6with the accelerating electrode omitted;

Fig. 8 is a fragmentary edgewise view of the modification of themounting assembly of Figs. 6 and 7 minus the accelerating electrode;

Fig. 9 is a fragmentary plan view of the modification of Fig. 8; and

Fig. 10 is a detail view of a portion of the sole adjacent the mountingassembly of Figs. 8 and 9.

Referring now to Figs. 1 to 4, a traveling wave tube oscillator 20 isshown which includes a periodic, frequency responsive energy translationstructure or anode delay line 22; a sole 30 maintained negative withrespect to anode 22; a lead-in assembly 40; an output coupling means 50;an electron gun mounting assembly 60 further including at least acathode 62 and heater 64 and a transverse magnetic field producingmeans, a portion of which is indicated in Pig. 1.

Anode assembly 22 comprises a circular interdigital delay line includinga plurality of interdigital fingers 24 and 24 which extend fromannularmembers 25 and 25', respectively. Members 25 and 25 are secured, as byscrews 26 (see Fig. 2), to the shoulder portion of a cyhndricalelectrically conductive ring 27. The remainder of the anode assemblyincludes a pair of oppositely disposed cover plates 28 and 29 attached,as by welding, to ring 27.

The sole 30 consists essentially of a cylindrical block of metal, suchas copper, having a recessed center portion 38 and a flange portion 39and containing a plurality of apertures 31 extending through saidrecessed surface 38. A centrally located aperture 32 is provided in thesole to permit the connection of lead-in assembly 40 and the passage ofexternal circuit connecting leads in a manner to be shown subsequently.

Lead-in assembly 40 includes a bipartite electrically conductivecylindrical tubular sleeve 42 which is inserted in an aperture in coverplate28 of tube 211? and is. welded or otherwise securely "attachedthereto.. A section of cylindrical glass tubing 43 serves tointerconnect metal sleeve 42 and a second metal sleeve 44. The other endof sleeve 44 is provided with a glass seal 45 for sealing the electricaldischarge device after evacuation. Sleeves 42 and 44 are preferablyconstructed of a material having an expansion coefficient closelyapproximating that of glass. The lead-in assembly is arrangedperpendicular to cover 28 of tube 20 and further includes an elongatedelectrically conductive tubular supporting cylinder 46 which acts as themain support for sole 30 as well as for cathode mounting assembly 40.One end of cylinder 46 is afiixed to the periphery of centrally locatedaperture 32 in sole 30. The other end of cylinder 46 contains anoutwardly flared portion 47 which is connected to the inner surface ofthe second sleeve 44. The necessary cathode and heater leads are fedthrough supporting cylinder 46 and are insulatedly supported therefromby glass beads 49.

The interdigital anode delay line 22 is arranged concentric with sole 30and is separated from the circumferential wall 33 of the sole to form aninteraction space 35 through which the electron beam generated by thecathode passes. Anode delay line 22 may be terminated at one end byattenuation, preferably in the form of an energy dissipative material,such as iron, which is applied to the fingers in the region over whichattenuation is desired. The coaxial line 50 is sealed in an opening ofwall 27 of the anode and impedance matched to the anode delay line.

The inner conductor 52 of coaxial output coupling means 50 is connectedto a finger at or adjacent the end of the periodic anode delay lineelectrically remote from the attenuation region.

Traveling wave tube 20 may, in some cases, be provided with a collectorelectrode 37, shown in Fig. 2, for intercepting electrons after onetraversal of the arcuate interaction space. This collector electrodepreferably takes the form of a projection from the back wall of theanode delay line and is located adjacent the cathode. The arrangement ofthis collector is shown in the aforesaid copending application.

Although the anode delay line has been described and illustrated as aninterdigital delay line, this invention is not limited thereto. Theanode delay line may, for example, consist of a loop-loaded wave guide,a strapped vane periodic structure, a strapped loop periodic structureor a disk loaded coaxial structure.

A suitable electric field between anode and sole may be obtained bymeans of a voltage applied between anode and sole. The sole may benegatively biased with respect to the cathode by means of a source 105of voltage connected between cathode lead 48 and tubular conductorsleeve 46. The cathode may, however, be at the same potential as thesole, if so desired. Similarly anode 22 may be maintained at a positivepotential relative to both sole and cathode by means of a source 107 ofvoltage connected between metal sleeves 42 and 44. Sleeve 42, by virtueof its electrical connection to cover plate 28, is at the sameelectrical potential as the anode.

A uniform magnetic field transverse to the direction of propagation ofthe electron beam is provided by either a permanent magnet orelectromagnet having cylindrical pole pieces and 81 radially positionedon or adjacent the tube. Pole piece 80 is apertured to receive theleadin assembly 40 and pole piece 81 is apertured to maintain symmetryof the magnetic field.v The flux lines should be concentrated in theinteraction space 35 between sole 30 and cylindrical anode 22.

By proper adjustment of the magnitude and polarity of the magnetic andelectric fields, the electron beam may be made to follow a circular patharound interaction space 35 under the combined influence of thetransversely disposed magnetic and electric fields previously referredto. V

The radio frequency energy generated in the interaction earth sets up ahigh frequency electromagnetic field which may be analyzed as a seriesof space harmonics, some of which travel in one direction (clockwise)along the anode structure, and others of which travel counter-clockwise,and all of which travel with different phase velocities. If the electronbeam, whose velocity is a function of the electric field strength, issynchronized with the proper space harmonic interaction of the beam,said space harmonic will result in the production of oscillations withinthe tube. The energy travels toward the' electron source and isextracted at the cathode end of anode delay line 212 by way of coaxialoutput line 50.

The cathode mounting assembly 60 for the tube of Fig.- 1 is shown inFigs. 3 and 4 and includes cathode 62 and heater 64, shown in detail inFig. 4. The cathode 62 is in the form of a rectangular prism providedwith a circular bore 63 in which a folded coated tungsten heater wire 64is 'insertcdj- The heater may be of the type used in standard receivingtubes and may be con nected at one end to the inner wall of the cathode.Cathode body 62 is preferably made of porous tungsten and the outersurfaces are coated with an emitter containing a compound of barium.This cathode not only is relatively small but operates at a relativelylow temperature. For example, a typical cathode now in use iapproximately 008 inch square and 0.8 inch long and operates at atemperature of approximately 950 degrees C. A corresponding directlyheated cathode made of tungsten ribbon, such as used in the aforesaidcopending application of Dench, operates at a temperature ofapproximately 2300 degrees C. A pair of molybdenum supporting leads 66and 67 are spot welded to opposite ends of the cathode body, as shown inFig. 4. By welding the leads at the ends of the cathode body, theheating effect is small and the barium emissive surface is not impaired.The cathode heater may, if desired, be con nected to the supporting lead66 at one end, as shown in Fig. 4. Although the supporting leads arepreferably made'of molybdenum, any electrically conductive materialcapable of withstanding temperatures of the order of 950 degrees C. maybe used. The cathode body is posit.oned within a recess or slot 68 inwall 33 of sole 30, as shown in Fig. 3.

Mounting assembly 60 includes a pair of parallel mica insulatingsupports 70 and 71 containing a plurality of apertures 73, each of whichreceives a metallic eyelet 74. The cathode supporting leads 66 and 67are welded to the eyelets in supports 70 and 71. One end of heater 64 isconnected to cathode supporting lead 66 and the other end of the heateris connected to a stake 79, which is mounted in support 70 in the samemanner as cathode supporting lead 66. Leads 66 and 67 should be goodradiators of heat in order that the temperature drop between the cathodebody at the point of attachment of the lead and the junction of theeyelet and the mica disk is a maximum. This is necessary in order tomaintain the mica at temperatures below approximately 600 degrees C., atwhich temperature mica starts to disintegrate into powder. Molybdenum isa good heat radiator in addition to being a refractory metal. In orderto further increase the heat radiation from the supporting leads, themetal may be roughened, as by sand blasting, and blackened. The micainsulating supports 70 and 71 are mounted to the sole by means of screws76.

The insulating supports 70 and 71 need not be made of mica, however. Forexample, a ceramic may be used which, although not as resilient as micato temperature changes, is capable of operation at higher temperatures.To allow for the smaller thermal expansion of the ceramic, however, itmay be desirable not to weld lead 67 to the corresponding eyelet insupport 71 but rather to allow it to slide freely within aperture 73 insupport 71, as indicated in Fig. 5.

To prevent contact of the metal eyelets and the sole,

with consequent shorting of the various electrodes, the cathode andheater leads are insulated from the sole by means of spacers 78 locatedbetween the mica supports and the face of the sole. These spacers arepreferably made of any material capable of withstanding heat. Althoughnot essential, thin molybdenum sheets 75, such as shown in Fig. 7, maybe positioned under the heads of each screw 76 in order to preventpossible damage to the mica supports resulting from pressure exerted bythe heads of the metal screws.

In order to substantially reduce the strain on the cathode and heaterresulting from connecting leads attached thereto, a pair of stakes 80and 81 may be provided for the cathode and heater leads, respectively,and

, respectively, by metallic cross bars 83 and 84, respectively.

It is often desirable to modulate a traveling wave oscillator by meansof a grid electrode to which the modulating signal is applied. Inaddition, the use of an accelerating anode serves to permit theproduction of a more suitable electron beam trajectory. In Fig. 6 amodification of the mounting assembly of Fig. 3 is shown for use withtraveling wave tubes having a grid 88 and an accelerating anode 90 inaddition to the usual cathode and heater. Cathode 62 and heater 64 aremounted as in Fig. 3. Fig. 7 is an edgewise view of the assembly of Fig.6 minus accelerating electrode 90.

Grid electrode 88 has a channel shaped portion 88 surrounding thecathode and an integral flat elongated portion 88" extending from thechannel to provide increased heat dissipation from the grid. Grid 88 ismounted from mica insulating supports 70 and '71 by means of leads 91and 92 attached at opposite ends of the grid, in the same manner thatthe cathode is mounted. Because of the configuration of the grid, alarger slot 68 must be provided than in the embodiment shown in Fig. 3.

Over a period of time, barium vapor accumulates on the mica supports ofthe mounting assembly of Figs. 1

and 3, owing to endwise evaporation from the cathode. This forms anelectrically conductive film on the underside of the supports andeventually causes a short circuiting of the leads. In order to preventthis from occurring, end caps 98 are provided on the portion of the gridoverlyingthe ends of the cathode to intercept the greater portion of theerrant vapors, as shown in Fig. 6.

An accelerating electrode 90 is positioned adjacent the grid and cathodeand includes a portion directly over the emitting area. The mainvportionof the accelerating electrode is substantially parallel to the elongatedportion 88' of grid 88, The parallel relationship of these portions ofthe grid and accelerating anode helps to maintain a proper electricfield therebetween. Accelerating anode 90 also includes a taperedportion 90 which serves mainly to facilitate heat dissipation therefrom.This portion of the accelerating anode may be omitted, if desired.

In order to accommodate the accelerating electrode 90, which islaterally displaced from the grid cathode assembly, insulating supports70 and 71 each comprise an extension to which the accelerator mountingleads 93 and 94 may be secured. A stake and cross bar may be providedfor the grid and accelerating electrodes, just as for the cathode andheater, as shown clearly in Fig. 6 As in the case of the tube of Fig. 1,the various leads which connect to the stakes are brought through aleadin assembly identical to that shown in Fig. 1, except that thenumber of leads is increased from two to four.

In Figs. 8 to 10 a modification of the electrode mounting assembly ofFigs. 6 and 7 is shown. In lieu of smu cathode and shields in the formof end caps 98 built on grid 88, a portion 99 of sole flange 39 is cutaway, as shown in' Fig. 10. An arcuate plate 100 is inserted within theslotted portion 99 and between the mica supports 70 and 71, as the casemay be, and the ends of the cathode, as shown in Fig. 9. This plate isapertured to receive the electrode-supporting leads and heater lead aswell as a pair of mounting screws 76. The thickness of plate 100 may beequal to the depth of cut in flange 39 of sole 30. Although theperiphery of end plate of shield 10%) is illustrated as being inalignment with the outer rim of sole flange 39, end plate 100 may extendoutward beyond the periphery of sole 30, as in Fig. 6,in the event thatan accelerating electrode is to :form a part of the electrode assembly.

This invention is not limited to the particular details of construction,materials and processes described, as many equivalents will suggestthemselves to those skilled in the art. For example, the mounting devicedescribed is not limited to use with tubes of cylindrical constructionbut may be applied equally as well to linear traveling wave tubes, suchas shown and described in an application for U8. Letters Patent of E. C.Dench, Serial No. 382,133, filed September 24, 1953. It is accordinglydesired that the appended claims be given a broad inter pretationcommensurate with the scope of the invention within the art.

What is claimed is:

1. An electron source for a traveling wave tube having a periodic,frequency-responsive anode and a principal electrode arranged parallelthereto comprising an elongated substantially polygonal cathode bodyhaving at least one surface spaced from and parallel to said anode andcontaining an electron emitting material disposed on at least said onesurface of said cathode body, and a heater positioned within theaperture in said body and spaced therefrom.

2. An electron source for a traveling wave tube having a periodic,frequency-responsive anode and a principal electrode arranged parallelthereto comprising an elongated porous cathode body positioned within aslot in said principal electrode and spaced from said anode,

said cathode body further having a longitudinal aperture therein forreceiving a heater, and an electron emitting material disposed on thesurface of said cathode body.

3. An electron source comprising a porous cathode body having anaperture therein, a supporting lead connected to each end of said body,an electron emitting material disposed on the outer surface of saidcathode body, and a heater positioned within the aperture in said bodyand spaced therefrom, one end only of said heater being connected to oneof said supporting leads and the other end of said heater extendingexternally of said cathode body, said supporting leads having anirregular surface coated with a black material for increasing the heatradiation therefrom.

4. An electrode mounting assembly comprising an apertured cathode, asupporting lead connected to each end of said cathode, a heaterpositioned within said cathode, first and second spaced electricallyinsulating mounting members each having an aperture therein forreceiving a supporting lead, said first mounting member furthercontaining first and second rigid affixed electrically conductiveelements, one end of said heater being electrically connected to saidfirst element and the other end of said heater being connected to saidone supporting lead, one of said supporting leads being electricallyconnected to said second element.

5. An electrode mounting assembly comprising an apertured cathode, asupporting lead connected to each end of said cathode, a heaterpositioned within and electrically insulated from'said cathode, firstand second spaced electrically insulating mounting members havingapertures therein bounded by eyelets, onegrsatu supporting leadsconnected to and extending through said eyelet in' said first member toform an electrical terminal, means including an electrically conductiveelement secured to said firstmember for connecting one endof said heaterthereto.

6. Anelectrode mounting assembly comprising a base forming part of anelectron tube, an apertured cathode, a supporting lead connected to eachend of said cathode, a heater positioned within and electricallyinsulated from said cathode, first and second spaced electricallyinsulating mounting members having apertures therein bounded by eyelets,one of said supporting leads connected to and extending through saideyelet in said first member to form an electrical terminal, meansincluding an electrically conductive element secured to said firstmember for connecting one end of said heater thereto, and means forattaching said mounting members to opposite por tions of said base.

7. An electrode mounting assembly comprising an apertured cathode, asupporting lead connected to each end of said cathode, a heaterpositioned within said cathode, first and second spaced electricallyinsulating mounting members each having apertures therein for receivinga supporting lead, one of said supporting leads connected to andextending through said aperture in said first member to form anelectrical terminal, the other of said supporting leads being adapted tomove freely in said aperture in said second member, and means includingan electrically conductive element secured to said first plate forconnecting one end of said heater thereto.

8. An electrode mounting assembly comprising an apertured cathode, agrid partially surrounding said cathode, a supporting lead connected toeach end of said cathode and said grid, a coil heater positioned withinsaid cathode, first and second spaced electrically insulating membershaving apertures therein, one each of said supporting leads connected toand extending through said aperture in said first mounting member toform electrical terminals, means including an electrically conductivepost secured to said first member for connecting one end of said heaterthereto, said grid being provided with end caps positioned adjacent theends of said cathode for preventing contamination of said first memberby lateral emission from said cathode, and apertures within one of saidend caps for insertion of said cathode supporting lead and said heater.

9. An electrode mounting assembly comprising. an apertured cathode, acontrol electrode partially surrounding said cathode for controlling thecurrent from said cathode, a supporting lead connected to each end ofsaid cathode and said control electrode, a coil heater positioned withinsaid cathode, first and second spaced electrically insulating mountingmembers having apertures therein bounded by eyelets, one each of saidsupporting leads connected to and extending through said eyelet in saidfirst member to form electrical terminals, means including anelectrically conductive post secured to said first member for connectingone end of said heater thereto, said control electrode being providedwith end caps positioned adjacent the ends of said cathode forpreventing contamination of said mounting members by lateral emissionfrom said cathode, and apertures within one of said end caps forinsertion of said cathode supporting lead and the ends of said heater.

10. An electrode mounting assembly comprising an apertured cathode, acontrol electrode partially surrounding said cathode for controlling thecurrent from said cathode, and an accelerating electrode positionedadjacent said cathode and control electrode, a supporting lead connectedto each end of said cathode, control electrode and acceleratingelectrode, a coil heater positioned within said cathode, first andsecond spaced electrically insulating mounting members having aperturestherein bounded by eyelets, one each of said supporting leads aa'rinla 9H connected to and extending through said eyelet in said first member toform electrical terminals, means including an electrically conductivepost secured to said first member for connecting one end of said heaterthereto, said control electrode being provided with end caps positionedadjacent the ends of said cathode for preventing contamination of saidmounting members by lateral emission from said cathode, and apertureswithin one of said end caps for insertion of said cathode supportinglead and said heater.

11. A traveling wave tube comprising a periodic frequency responsiveenergy translation structure for transmitting electromagnetic waveenergy and constructed to produce adjacent thereto fields of the waveenergy being transmitted, a principal electrode spaced from andsubstantially coextensive with said translation structure and maintainedat a potential negative with respect thereto, a plurality of associatedelectrodes including a cathode for emitting electrons, and means fordirecting a beam of said electrons along the space between saidstructure and said principal electrode and in energy interactingrelation with said fields, a pair of electrically insulating supportmembers electrically insulated from and afiixed to opposite portions ofsaid principal electrode, a supporting lead connected to each end ofeach of said associated electrodes, said insulating support memberscontaining apertures for receiving said supporting leads, and means forsecuring said supporting leads to said support members.

12. A traveling wave tube comprising a periodic frequency responsiveenergy translation structure for transmitting electromagnetic waveenergy and constructed to produce adjacent thereto fields of the Waveenergy being transmitted, a principal electrode spaced from andsubstantially coextensive With said translation structure and maintainedat a potential negative with respect thereto, a plurality of associatedelectrodes including a cathode for emitting electrons and a controlelectrode for controlling the electrons emitted from said cathode, andmeans for directing a beam of said electrons along the space betweensaid structure and said principal electrode and in energy interactingrelation with said fields, a pair of electrically insulating supportmembers electrically insulated from and aifixed to opposite portions ofsaid principal electrode, a supporting lead connected to each end ofeach of said associated electrodes, said insulating support memberscontaining apertures for receiving said supporting leads, an eyeletsurrounding said apertures and affixed to said insulating supportmembers, and means for securing said supporting leads to correspondingones of said eyelets.

13. A traveling wave tube comprising a periodic frequency responsiveenergy translation structure for transmitting electromagnetic waveenergy and constructed to produce adjacent thereto fields of the waveenergy being transmitted, a principal electrode spaced from andsubstantially coextensive with said translation structure and maintainedat a potential negative with respect thereto, a

plurality of associated electrodes including a cathode foremittingelectrons and an electron current control electrode partiallysurrounding said cathode, and means for directing a beam of saidelectrons along the space between said structure and said principalelectrode and in energy interacting relation with said fields, a pair ofelectrically insulating support members electrically insulated from andaflixed to opposite portions of said principal electrode, a supportinglead connected to each of said associated electrodes, said insulatingsupport members containing apertures for receiving said supportingleads, an eyelet surrounding said apertures and afiixed to saidinsulating support members, means for securing said supporting leads tocorresponding ones of said eyelets, and means including a portion ofsaid electron current control electrode for shielding said supportmembers from said cathode.

14. A traveling wave tube comprising a periodic frequency responsiveenergy translation structure for trans- 10 a mitting electromagneticwave energy and constructed to produce adjacent thereto fields of thewave energy being transmitted, a principal electrode spaced from andsubstantially coextensive with said translation structure and maintainedat a potential negative with respect thereto, a plurality of associatedelectrodes including a cathode for emitting electrons and a currentcontrol electrode partially surrounding said cathode, and means fordirecting a beam of said electrons along the space between saidstructure and said principal electrode and in energy interactingrelation with said fields, a pair of electrically insulating sup: portmembers electrically insulated from and fixedly mounted with respect toopposite portions of said principal electrode, a supporting leadconnected to each end of each of said associated electrodes, saidinsulating support members containing apertures for receiving saidsupporting leads, an eyelet surrounding said apertures and affixed tosaid insulating support members, means for securing said supportingleads to corresponding ones of said eyelets, and means including a plateattached to said principal electrode for shielding said support membersfrom said cathode.

15. An electrode mounting assembly comprising a cathode, a supportinglead connected to each end of said cathode, and first and secondelectrically insulating mounting members fixedly supported in spacedrelationship, each of said supporting leads being supported by andextending through a corresponding one of said members.

16. An electrode mounting assembly comprising a cathode, a supportinglead connected to each end of said cathode, and first and second spacedelectrically insulating mounting members each having apertures thereinfor receiving a corresponding supporting lead, one of said supportingleads extending through said aperture in said first member and securedto said first member to form an electrical terminal, the other of saidsupporting leads being adapted to move freely in said aperture in saidsecond member.

17. An electrode mounting assembly comprising a cathode, a gridpartially surrounding said cathode, a supporting lead connected to eachend of said cathode and said grid, first and second spaced electricallyinsulating mounting members having apertures therein, one each of saidsupporting leads extending through a corresponding aperture in saidfirst mounting member and supported by said first mounting member toform electrical terminals, said grid being provided with end capspositioned adjacent the ends of said cathode for preventingcontamination of said first member by lateral emission from saidcathode, and apertures within one of said caps for insertion of saidcathode supporting lead.

18. An electrode mounting assembly comprising a cathode, a controlelectrode partially surrounding said cathode for controlling the currentfrom said cathode, a supporting lead connected to at least one end ofsaid cathode and said control electrode, at least one rigid supportplate afiixed in space, at least one electrically insulating mountingmember electrically insulated from and maintained in spaced relationshipwith said support plate, said supporting leads being connected to saidmounting member and extending through said support plate and saidmounting member to form electrical terminals, said support plate beingpositioned to prevent contamination of said mounting member by lateralemission from said cathode.

19. A traveling wave tube comprising a periodic energy translationstructure for transmitting electro magnetic wave energy and constructedto produce adjacent thereto fields of wave energy being transmitted, aprincipal electrode spaced from and substantially coextensive with saidtranslation structure, a plurality of associated electrodes including acathode for emitting electrons and an electron control electrodepartially surrounding said cathode, means for directing a beam of saidelectrons along the space between said structure and said principalelectrode and in energy interacting relation with said fields, a pair ofelectrically insulating support memberselectrically. insulated from andafiixed to opposite portions of said principal electrode, a supporting.lead connected to each end of each of said associated electrodes, saidinsulating support members containing apertures for receiving saidsupporting leads, and means for securing each of said supporting leadsto said support members.

20. A traveling wave tube comprising a periodic energy translationstructure for transmitting electromagnetic Wave energy and constructedto produce adjacent thereto fields of wave energy being transmitted, aprincipal electrode spaced from and substantially coextensive with saidtranslation structure, a plurality of associated electrodes including acathode, for emitting electrons and an electron control electrodepartially surrounding said cathode, means for directing a beam of saidelectrons along the space between said structure and said principalelectrode and in-energy interacting relation with said fields, a pair ofelectrically insulating support members electrically insulated from andaffixed to opposite portions of said principal electrode, a supportinglead connected to each end of each of said associated electrodes, saidinsulating support members containing apertures for receiving saidsupporting leads, means for securing each of said supporting leads tosaid support members, and means including a portion of said controlelectrode for shielding said support members from lateral emission fromsaid cathode. 21. A traveling wave tube comprising a periodic energytranslation structure for transmitting electromagnetic wave energy andconstructed to produce adjacent thereto fields of wave energy beingtransmitted, a principal electrode spaced from and substantiallycoextensive with said translation structure, a plurality of associatedelectrodes including a cathode for emitting electrons and a controlelectrode partially surrounding said cathode, means for directing a beamof said electrons along the space between said structure and saidprincipal electrode and in energy interacting relation with said fields,at least one electrically insulating support member electricallyinsulated from and afiixed to a portion of said principal electrode, atleast one supporting lead connected to each of said associatedelectrodes, said insulating support member containing apertures forreceiving said supporting leads, means for securing each of saidsupporting leads to said support member.

22. A traveling wave tube comprising a periodic energy translationstructure for transmitting electromagnetic wave energy and constructedto produce adjacent thereto fields of wave energy being transmitted, aprincipal electrode spaced from and substantially coextensive with saidtranslation structure, a plurality of associated electrodes including acathode for emitting electrons and a control electrode partiallysurrounding said cathode, said cathode being apertured to receive aheater element, means for directing a beam of said electrons along thespace between said structure and said principal electrode and in energyinteracting relation with said fields, at least one electricallyinsulating support member electrically insulated from and aflixed to aportion of said principal electrode, at least one supporting leadconnected to each of said associated electrodes, said insulating supportmember containing apertures for receiving said supporting leads and saidheater, means for securing each of said supporting leads to said supportmember.

23. A traveling wave tube comprising a periodic energy translationstructure for transmitting electromagnetic wave energy and constructedto produce adjacent thereto fields of wave energy being transmitted, aprincipal electrode spaced from and substantially coextensive with saidtranslation structure, a plurality of associated electrodes including acathode for emitting electrons and a control electrode partiallysurrounding said cathode, means for directing a beam of said electronsalong the space between said structure and said principal electrode andin energy interacting relation with said field, at least oneelectrically insulating support member electrically insulated from andafiixed to a portion of said principal electrode, at least onesupporting lead connected to each of said associated electrodes, saidinsulating support member containing apertures for receiving saidsupporting leads, means for securing each of said sup-porting leads tosaid support member, and means including a portion of said controlelectrode for shielding said support member from lateral emission fromsaid cathode.

24. A traveling wave tube comprising a periodic energy translationstructure for transmitting electromagnetic Wave energy and constructedto produce adjacent thereto fields of wave energy being transmitted, aprincipal electrode spaced from and substantially coextensive with saidtranslation structure, a plurality of associated electrodes including acathode for emitting electrons and a control electrode partiallysurrounding said cathode, said cathode being apertured to receive aheater element, means for directing a beam of said electrons along thespace between said structure and said principal electrode and in energyinteracting relation with said field, at least one electricallyinsulating support member electrically insulated from and afiixed to aportion of said principal electrode, at least one supporting leadconnected to each of said associated electrodes, said insulating supportmember containing apertures for receiving said supporting leads and saidheater, means for securing each of said supporting leads to said supportmember, and means including a portion of said control electrode forshielding said support member from lateral emission from said cathode,said last-named means being apertured to permit passage of said heaterelement.

25. A traveling wave tube comprising a periodic energy translationstructure for transmitting electromagnetic wave energy and constructedto produce adjacent thereto fields of wave energy being transmitted, aprincipal electrode spaced from and substantially coextensive with saidtranslation structure, a plurality of associated electrodes including acathode for emitting electrons and an electron control electrodepartially surrounding said cathode, means for directing a beam of saidelectrons along a space between said structure and said principalelectrode and in energy interacting relation with said field, a pair ofrigid mounting plates adapted to be fixedly mounted to opposite portionsof said principal electrode, a pair of electrically insulating supportmembers electrically in sulated from said mounting plates and mounted inspaced relation with respect to corresponding ones of said rnountingplates, a supporting lead connected to each end of each of saidassociated electrodes, said insulating support members containingapertures for receiving said supporting leads, and means for securingsaid supporting leads to corresponding ones of said supporting members.

26. A traveling wave tube comprising a periodic energy translationstructure for transmitting electromagnetic wave energy and constructedto produce adjacent thereto fields of wave energy being transmitted, aprincipal electrode spaced from and substantially coextensive with saidtranslation structure, a plurality of associated electrodes including acathode for emitting electrons and an electron control electrodepartially surrounding said cathode, means for directing a beam of saidelectrons along a space between said structure and said principalelectrode and in energy interacting relation with said field, at leastone electrically insulating support member electrically insulated fromand affixed to a portion of said principal electrode, at least onesupporting lead connected to each of said associated electrodes, saidinsulating support member containing apertures for receiving saidsupporting leads, and means for securing each of said supporting leadsto said support member.

27. A traveling wave tube comprising a periodic energy translationstructure for wave energy and constructed to produce adjacent theretotransmitting electromagnetic fields of Wave energy being transmitted, aprincipal electrode spaced from and substantially coextensive with saidtranslation structure, a plurality of associated electrodes including acathode for emitting electrons and an electron control electrodepartially surrounding said cathode,

means for directing a beam of said electrons along a space between saidstructure and said principal electrode and in energy interactingrelation with said fields, at least one electrically insulating supportmember electrically insulated from and affixed to a portion of saidprincipal electrode, at least one supporting lead connected to eachReferences Cited in the file of this patent UNITED STATES PATENTSWillshaW Jan. 8, 1952 Ludi Dec. 16, 1952 v UNITED STATES PATENT OFFICECERTIFICATION OF CORRECTION Patent No., 2,971,112 February 7, 1961Edward C. Dench It is hereby certified that error appears in the abovenumbered patent requiring correction and that the said Letters Patentshould read as corrected below;

Column 8, lines 36 and 37, after "insulating" insert mounting column 12,lines 24, 46, and 67, for "held", each occurrence, read fields Signedand sealed this 27th day of June 1961,

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents

